As desperate Zimbabwean refugees pile off the buses in downtown Johannesburg, they do not dare to dream that change is on its way.

Teppina Ntombela, 32, who left three children behind to come looking for work in South Africa, said: "We are scared. Mugabe will not go easily. But unless I am here earning money my children will not eat. I send them cooking oil and rice because there is nothing there. Shelves are bare."

For the thousands of Zimbabweans fleeing every day - dodging patrols, cutting through game parks, hiding under canvas in trucks - South Africa at least offers a chance to earn cash and send food back home.

But life across the border for the illegal immigrants, now estimated at up to three million, remains a humiliating struggle. Some say they are at the mercy of corrupt local police and many among the South African population resent their presence.

Oscar Machapaza, 34, was a teacher in Harare. As he lay on a Johannesburg church floor with 1,500 others, he said: "I've lost my honour. I work on a building site and sleep on a dirty floor. There are no blankets but disease and lice.